Various training devices have been known as disclosed in Japanese Patent Laid-Open No. 2009-45236 for example. When training is conducted, various training devices (training machines) are often used depending on purposes. There are a wide variety of situations where training is conducted. To accomplish various objects, training is conducted in various scenes including muscle training for healthy people and athletes, a preventive care for elderly people, or a convalescent rehabilitation.
Meanwhile, in recent years, research on induction of muscle activities by using electrical stimulation and the like is being pursued with respect to a walking assist system for persons having difficulty in walking due to disabilities, such as cranial nerve palsy. In this regard, research fields such as brain-machine interface (BMI) and neuro-rehabilitation are being active. Related technical literatures include, for example, “Development of a reflex electrical stimulation device to assist walking” by Hiroshi Yokoi, et al. in BRAIN and NERVE-Progress in research of nerve, issued on November 2010, vol. 62, No. 11 “Walking and Abnormalities” (“Hokou to Sonoijou” in Japanese). In practical applications of research achievements in such fields, training to do walking and other actions correctly (smoothly) to some extent and/or training for restoring muscle force used therefor are needed for persons with disabilities to recover to the level of being able to return to everyday life.